A sleep expert explains why you need lighter, breathable blankets this summer

Globe and Mail

a day ago

As temperatures climb, most people naturally adjust their routines: more patio time, fewer layers, an uptick in ice cream consumption.
But overlooking one key change at bedtime could sabotage your slumber during the warmer months. As hot nights lead to restless sleep, too many of us keep using our winter-weight bedding.
A seasonal swap to lighter, breathable blankets isn't just about aesthetics (though breezy linens and nautical stripes can transform a bedroom into something more beach-y and fun). Experts say it could also be one of the simplest ways to deepen your sleep from June to September.
'Changing blankets seasonally can help improve sleep quality by keeping your body at a comfortable temperature,' says Armin Rahmani, a psychiatrist and sleep medicine specialist. 'Since your thermal needs vary depending on the season, using the same blanket year-round may not provide the best sleep environment.'
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Overheating at night is more than just uncomfortable. 'It can reduce the amount of deep sleep you get, which is critical for feeling rested,' explains Rahmani, who also sits on the board of the Canadian Sleep Society, an advocacy group whose goal is to improve sleep for all Canadians. 'Even mild discomfort from feeling too warm can lead to more fragmented sleep and lighter sleep stages.'
Losing sleep over your blanket might sound ironic, even silly, but the consequences can be serious. The Canadian Institutes of Health Research links chronic sleep deprivation to a multitude of issues, including cardiovascular disease, diabetes, hypertension and poor mental health. And Canadians aren't exactly getting enough shuteye as it is. According to a 2023 survey by Narrative Research, just 16 per cent of us report sleeping well all seven nights of the week.
Blankets are not the only cause. Tariffs, politics and a slumping economy are among the many stressors likely keeping us tossing and turning. But it's still worth asking: What should you be snuggling up with when it's more than 25 degrees at midnight?
To get clues, Rahmani points to a recent systematic review published in the Journal of Sleep Research. 'The findings highlight that the relationship between bedding materials and sleep is complex,' he says. 'No single blanket type is ideal for everyone. But generally, lighter, breathable materials may benefit those who tend to overheat or sleep in warmer environments.'
Insulative materials such as wool and down, he notes, are generally better for chillier seasons.
Sogol Asghari, president of Canada's Institute of Textile Science, agrees. 'The most suitable blankets for summer are made from breathable, moisture-wicking and lightweight materials,' she says. 'Fabrics with loose weaves promote airflow and help regulate body temperature during sleep.'
Both experts suggest natural fibres such as linen, cotton and bamboo. 'Studies show linen can improve sleep quality under warm conditions, especially in young adults,' Rahmani says. 'For cotton, which can be relatively affordable, look for lightweight, percale-weave cotton for a cooler feel. Bamboo-based fabrics are antimicrobial and naturally cool to the touch.'
There can also be environmental pluses, depending on the fabrics. 'From a sustainability perspective, organic cotton and bamboo are appealing options for ecoconscious consumers – when responsibly sourced,' Asghari adds. Look for seals of approval from organizations such as OEKO-TEX, which screens for products detrimental to human health, or the Forest Stewardship Council, which notes the companies that responsibly grow products like bamboo.
As for what to avoid? 'Polyester and other synthetic materials may trap heat and sweat, which can disrupt sleep, especially for hot sleepers,' Rahmani says.
In short, aim for anything comfortable. If you're waking up tangled in sweaty sheets or peeling polyester off your legs at dawn, your blanket might be unfit for the season. Summer sleep should feel like bliss, not bedlam.
A good summer blanket begins with a natural and lightweight fabric.